2010/05/21 by Stephen Jewson, Jewson, Stephen, Dan Rowlands +3
Earth and Planetary Sciences · Environmental Science · Physics and Astronomy · #Atmospheric and Environmental Gas Dynamics #Atmospheric and Oceanic Physics (physics.ao-ph) #Climate variability and models #FOS: Physical sciences #Meteorological Phenomena and Simulations #physics.ao-ph
paper · pdf · doi:10.48550/arxiv.1005.3907
arxiv created 2010/05/21 · openalex publication_date 2010/05/21 · arxiv updated 2010/05/24 · openalex created_date 2025/10/24 · openalex updated_date 2026/07/28
Objective probabilistic forecasts of future climate that include parameter uncertainty can be made by using the Bayesian prediction integral with the prior set to Jeffreys' Prior. The calculations involved in determining the prior can then be simplified by making parametric assumptions about the distribution of the output from the climate model. The most obvious assumption to make is that the climate model output is normally distributed, in which case evaluating the prior becomes a question of evaluating gradients in the parameters of the normal distribution. In previous work we have considered the special cases of diagonal (but not constant) covariance matrix, and constant (but not diagonal) covariance matrix. We now derive expressions for the general multivariate normal distribution, with non-constant non-diagonal covariance matrix. The algebraic manipulation required is more complex than for the special cases, and involves some slightly esoteric matrix operations including taking the expectation of a vector quadratic form and differentiating the determinants, traces and inverses of matrices.